Telephone-exchange system.



L. H. JOHNSON. TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED IuLY 29.1916.

' Patented Feb513, 1917.

//v venfol i Lew/s H. Johnsoh LEWIS H. JOHNSON, OF BLOOMFIELD, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMZPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters'latent.

Patented Feb.

Application filed July 29, 1916. Serial No. 112,043.

To all whom it may concern:

Be it known that I, LEWIS H. a citizen of the United States, residing at Bloomfield, in the county of Essex and State of New Jersey, have invented certainnew and useful Improvements in TelephoneExchange Systems, of which the followingis a full, clear, concise, and exact description.

This invention relates to telephone exchange systems and more particularly to such systems having link circuits which may be employed for indiscriminately interconnecting common battery and magneto or local battery telephone lines terminating at a central oflice- The object of this invention is the production of improved signaling means for such telephone exchange systems.

In accordance with a feature of this invention, a link circuit is provided with a re lay operating upon connection of the link circuit with a line for causing the energization of another relay,-a locking circuit for which is established by the dcenergization of the first relay. The deenergization of the locked up relay followed by the energization of a supervisory relay causes a sig naling device to furnish an intermittent signal.

This invention is illustrated in the acconr panying drawing in which all apparatus is shown in its normal and unactuated condition.

There is shown in the drawing a telephone exchange system containing one embodiment "of this invention and comprising subscribterminate at the central ers stations A and B connected with lines terminating at a central otfice, and a universal cord circuit C located thereat for in terconnecting the subscribers stations. it will be understood that a plurality of lines cities, but for the sake of simplicity only the two lines are shown. Station A is of the common battery type, while station B is of the magneto type. The universal cord circuit C may be used indiscriminately to connect two magneto telephone lines, two common battery lines or a magneto and a common battery line. It is believed that this inventionwill be fully understood from a description of the operation oft-he system shown in the drawing, and it will be so described.

upposing subscriber A Wishes to converse With subscriber B, A will signal the JonNsoN,

central office in the usual manner by causing line signal 5 to be lighted. The operator, observing the line signal 5, inserts the answering plug in the jack indicated by this line signal, and thereby causes the opera relay 11, lower normal contact of'relay 45,

ring conductor of the cord circuit C, ring contacts of the answering plug and ack,

.over the line circuit tip contacts of the jack and answering plug, tip conductor of the cord circuit and upper normal contact of relay :45, to ground. The operation of relay 1' causes the operation of a differential listening relay 15 over a circuit from'batter 1 through the upper winding of listening relay 15, lower contact of relay 7 and con-- tact 16 of relay 17 to ground. The operation of the listening relay connects telephone set across the talking strands of the cord circuit. The operation of the listening relay 15 also causes the operation of relay 20 over a circuit from battery through the winding of relay 20, lower alternate contact of relay 15, contact of supervisory relay ll, resistance 9 and alternate contact of relay 6 to ground. The winding of relay 20 is then in parallel .with the lamp 10, so that the lamp does not light when the answering plug is inserted in the jack of the calling line. The operation of this relay 2O partially completes a locking circuit for itself, the complete locking circuit of which. may be traced from battery through the winding of relay 20, alternate contact thereof and contact 21 of relay 15, (which is closed upon the denergization of relay 15) contact of the supervisory relay 11, resistance 9 and the alternate contact of relay 6 to ground.

Finding the desired number to be that of subscriber B, the operator inserts the calling plug into the "jack of Bs line, th e'rehy causing the operation of relay 1? and cut-ofi relay 18 over a circuit from battery through the lower Winding of relay 1?, lower nor As soon as the answerin the operators circuit from battery .mal contact of marginal relay 19 and the winding thereof, upper winding of relay 17, sleeve contacts of the calling plug and jack and the winding of cut-off relay 18 to ground. I

Relay 19 is marginal and does not operate when in circuit with the cut-off relay of the magneto line, the winding of this cut-oil relay being of comparatively high resistance. Relay 17, in operating, opens its normal contact and closes its alternate contacts. The opening of the normal contact removes the short circuit from the lower winding of the differential listening relay 15, whereupon the magnetizing influence of the two windings of this relay neutralize each other so 1 that the relay releases its armatures and dis connects the operators telephone set from the cord circuit and completes the hereinbefore described locking circuit of relay 20. The closure of the lower alternate contact of relay 17 causes the operation of relay 25 over a circuit from battery through the winding of relay 25,,the upper normal contact of relay 19 and the lower alternate contact of relay 17 to ground. The operation of relay 25 bridges relay 26 across the talk ing strands of the cord circuit. Subscriber B may be signaled by the actuation of a ringing key 27 which connects a source of ringing current 28 to Bs line. Subscriber 13, upon removing the receiver from the switchhook in response to the signal, is in direct communication with subscriber A. Upon the'coinpletion of the conversation, subscriber A restores his receiver to the switchhook and causes the deenergization of supervisory relay 11, which opens the shunt circuit about the lamp 10, whereupon supervisory lamp 10 lights to furnish a disconnect signal. I The circuit for this lamp is from battery through the lamp resistance 9 and the alternate contact of relay 6 to ground. Subscriber B, when the conversation has been completed, gives the crank oi his generator 80 a short turn, causing the operation of relay 26, which in turn causes the operation of relay 31 over a circuit from battery, through the calling supervisory lamp 352, winding of relay 31 and contact of relay-26 to ground. Relay 31, in operating, establishes a locking circuit for itself from battery through the lamp 82, windingof relay 31, right-hand contact thereof and contact 38 of key 34 to ground. The operatlon of relay 31 also connects an interrupter, 39 'in circuit with the resistance 35,

I both being in parallel with the lamp 32.

The lamp 32 will thereby be caused to flash intermittently to furnish a characteristic disconnect signal from the station connected 5 to the magneto line. The operator upon receiving the disconnect signals may with draw the-plugsfrom the jacks, whereupon all apparatus returns to normal.

However, should subscriber A, before the answering plug is withdrawn from the jack of his line, wish to make a recall, the mere removal of the receiver from the switchhook causes the answering supervisory lamp 10 to be lighted intermittently to furnish a recall signal from the station connected with the common battery line. When A restored the'receiver to the switchhook, the supen visory relay 11, asbe'fore explained, was released, opening its contact. The opening of this contact interrupted the locking circuit of relay 20 which thereupon released. The subsequent energization of the supervisory relay 11, due to subscriber A removing the receiver from the switchhook, connects an interrupter :10 and a resistance &1 in parallel with the lamp l0, whereupon the lamp will be intermittently lighted to furnish the recall signal. The operator, observing the flashing of lamp 10, mayactuate the key 31, thereby short-circuiting the lower winding of the diflerential listening relay 15, permitting this relay to operate to connect the operators telephone set to the talking strands of the cord circuit. The operation of this listening relay also causes the operation of relay 20 over the heroinbefore traced circuit. The operation of the listening relay 15 and relay 20 interrupts the shunt circuit of lamp 10, so that the lamp ceases to flash.

Should the originating call be made by a subscriber on a magneto line, the plugging of the answering cord into the ack of such a line causes the operation of the cut-01f relay associated with that line and relay 7, relay 6 being marginal and operating when in series with the low resistance winding of the cut-off relay associated with the common battery line, but not operating when in series with the high resistance winding of the cut-off relay of a magneto'line. The operation of relay 7 causes the operation of relay 45 over a circuit from battery through 1 the winding of; relay 1-5, upper contact of relay 7 and normal contact of relay 6 to ground. The operation. of relay 4:5 bridges relay 46 across the talking strands oi" the cord. It will be noted that the operation of relay 7 causes the operation of the listening. relay in precisely the same manner as when the answering plug is inserted into the ack oi a common battery line.

When the calling magneto subscriber relay 47,:irepIacedi in parallel relation to e it-lashing signal. qcordclrcuit be connected with 'a'fcommon fthe lamp 10, whereupon this lamp is lighted intermittently to furnish a characteristic disconnect signal. from a station on a mag- ;neto l1ne,

whereby the operator furnished a signal, ofthe same character asthe'recall signahfrom a connectedcommon battery line. It will be seen therefore that the operator has to challenge only when observing a If the calling end of the battery line, marginal relay .19 will operate,

' lays, a locking circuit for the third relay.

. preventing the answers, ates, whereupon reslstance isplaced in shuntvofthe lamp 32, which is thereby efi'aced.

operation of, relay 25' and causing'th'e lamp 32 to be lighted over a cir-' cuit from batterythrough the lamp, lower alternate contact 'of relay T9, winding there; of, upper winding of relay 17, sleeve contacts of the calling plugand jack and the Winding of the cut-off relay to ground.

When the called common battery subscriber calling supervisory relay 48 oper- What is claimed is: I 1. A telephone exchange system compri ing a plurality of subscribers lines, a link circuit for interconnecting pervisory relay and a second when the link circuit is connected with athe lines,-a surelay operating calling line, a third relay actuated upon the operation of the supervisory and second reestablished upon thedeenergization of the second relay, a signaling device, and a source of interrupted current brought into circuit with the signaling device upon the subsequent deenergization of the third relay and the energization of the supervisory relay.

a ing a plurality of subscribers lines, a link circuit for interconnecting 'the lines, a supervisory relay and a second relay energized 3. A telephone exchange' system compris ing a' plurality of subscribers lines, a link circuit for interconnecting the lines, a supervisory relay for'the link'circult, a

visory 2. A telephone exchange vsystem compris-- supervisory signaling device, telephone set, a listening relay operating upon connection of the link circuit with -a line to include the operators telephone set operation of the listening relay, a locking circuit therefor closed by the deenergization of the listening relay, the deenergization of an operators in'circuit, a third'relay energized upon the the "supervisory relay causing the deenergization of the third relay, brought into operative relation with the signaling device by third relay and the subsequent energization I relay to cause the signal-: ing device to furnish an intermittent signal.

of the supervisory 4. A telephone exchange system comprising a plurality of subscribers lines, a link circuit for interconnecting the lines, a supervisory relay, an operators telephone set, a listening .relay operating when the link c1rcuit is connected with a line to include the operators telephone set in circuit, a third relay actuated upon the operation of the listening relay, a locking circuit for the third relay established upon the deene'rgization of the listening relay, a signaling device, interrupter mechanism brought into operative relationfwith the signaling device by the deenergization of the third relay and the subsequent energization of the super for causing the subsequent energization of the listening relay to interrupt the operative association of the interrupter mechanismrelay, and an operator controlled key and an interrupter 4 the deenergiz'ation of'the and the. signaling'devlce and to again include the operators telephoneset in circuit. 5'. A telephone exchange system, comprising a plurality of subscribers lines, a link circuit for interconnecting the lines, a supervisory relay, an operators telephone set, a listening relay operating when the link circuit is connected with a line to include the operators telephone set in circuit, a third .relay act'fiated'upon the operation of the listening relay, a locking circuitfor the third relay established upon the (lei nergization of the listening relay, a signaling device, interrupter mechanism brought into operative relation with the signaling device by the deenergization of the third relay and the subsequent energization of the supervisory relay, and an operator controlled key for causing the subsequent energization of the listening relay to again include the operators telephone set in circuit, the actuation of the listening relay causing the energiza: .tion of the third relay to interrupt the operative association of. the interrupter mechanism and the signaling'device.

In Witness whereof, I hereunto subscribe my name this 28 dayof July A. D., 1916.

' LEWIS H. JOHNSON. 

